1. Technical Field
The present invention relates to a female quick coupling fitting element for pipes.
For the transmission of fluids, fittings which may be rapidly reciprocally coupled to connect rigid or flexible pipes, in turn connected to a fluid feed or user, must frequently be used.
2. Description of the Related Art
The known quick coupling fittings usually consist of two elements, called male and female, which are fastened to respective pipes to be joined and which can be reciprocally coupled by screwing or snapping.
According to a currently known technique, the female element comprises an internal hollow body with an end provided with fastening means to one of the pipes to be joined and to a hollow external body that is coaxial with the internal body and having an end which axially protrudes with respect to the other end of the internal body opposite to that provided with fastening means.
The internal body coaxially supports a rigid central stem having a widened end near the protruding end of the external body. With the widened end, a sealing bush axially sliding and coaxially arranged about the stem is elastically stressed to engage to prevent the passage of fluid within the female element.
An elastically stressed cleaning bush is coaxially arranged about the sealing bush to prevent the entrance of dirt about the sealing bush.
Finally, a sliding or turning sleeve is envisaged about the protruding end of the external body which is snappingly engageable or screwed with a complementary end of the male element to ensure the stable union of the two male and female elements of the fitting.
For supporting and fastening the stem to the internal body of the female element, a transversal base is provided in some known fittings with circumferentially arranged shaped holes axially and radially locked by mechanical stops made between the fastening nut and the corresponding end of the internal body. The stem is fixed to the base by means of a terminal thread which passes through the base and a lock nut placed on the opposite side of the base itself.
An example of a fitting of this type is described in EP-A-0 542 342.
In this fitting, the stem must withstand the hydraulic pressure possibly existing within the female element and the elastic action exerted by the sealing bush of the female element, as well as the elastic force exerted, with elements coupled, by the springs of the male element. It may thus occur in time that the threaded fastening of the stem to the base may slacken and the lock nut may slip off, entering into circulation in the hydraulic system to which the fitting belongs.